Heat-preserving boiler

ABSTRACT

The invention adds to a heat preserving boiler of the type including a water tank, a flue pipe extending vertically therethrough, and a combustion chamber disposed under the water tank, apparatus for improving the efficiency including a drum spaced from and surrounding the water tank to form an annular downward outlet air passage between the outer surface of the water tank and the inner surface of the drum, a cover spaced about the drum to form an annular upward outlet air passage between the outer surface of the drum and the inner surface of the cover, a housing spaced about the cover to form an annular inlet air passage, and an outlet duct connected with the upward outlet air passage to lead exhaust gases to the atmosphere, the outlet duct being disposed within the inlet duct to form an extended inlet air passage.

United States Patent Kobayashi Dec. 26, 1972 HEAT-PRESERVING BOILERInventor: Shiro Kobayashi, Nagoya, Japan Assignee:

Nagoya-shi, Japan Filed: Sept. 24, 1971 Appl. No.: 183,521

Foreign Application Priority Data I Jan. 26, 1971 Japan ..46l294l US.Cl. "122/17, 126/85 B m. 01 ..F22b 9/02 Field of Search ..l22/17; 126/85B, 350

References Cited UNITED STATES PATENTS 5/l963 Vitale ..122/l7 PalomaKogyo Kabushiki Kaisha, 57

1/1970 Kramer .Q ..l22/l7 Primary Examiner-Kenneth W. SpragueAttorney-Barman, Davidson and Berrnan ABSTRACT The invention adds to aheat preserving boiler of the type including a water tank, a flue pipeextending vertically therethrough, and a combustion chamber disposedunder the water tank, apparatus for improving the efficiency including adrum spaced from and surrounding the water tank to form an annulardownward outlet air passage between the outer surface of the water tankand the inner surface of the drum, a cover spaced about the drum to forman annular upward outlet air passage between the outer surface of thedrum and the inner surface of the cover, a housing spaced about thecover to form an annular inlet air passage, and an outlet duct connectedwith 7 Claims, 5 Drawing Figures PATENTED nan 2 6 m2 R O T N E V m SH/R0 KOBA YA 671/,

BY 1% 5 I mm f ATTORNEYS HEAT-PRESERVING BOILER BACKGROUND OF THEINVENTION The present invention relates to a heat-preserving boiler, andmore particularly to an improved apparatus providing better combustion,heating and heat-preserving effects for the heat-preserving boiler.

In conventional types of heat-preserving boilers, a common outlet airpassage is usually provided which simply extends vertically upward froma combustion chamber through the central portion of a water tank and isconnected to a vertical chimney or the like. Counter-blow check means isdisposed between the passage and the chimney. Thus, a strong windpressure blowing into the chimney closes the check means and causes theexhaust gases to remain stagnantly at the level of the counter-blowcheck means rather than move from the combustion chamber into theatmosphere through the chimney. This causes incomplete combustion withinthe combustion chamber which is dangerous and uneconomic.

To eliminate the above disadvantage, a large diameter, long and verticalchimney has been applied and affixed onto the outlet air passage, butthis has served only to limit the placement of the boiler, noimprovement being obtained from the new appended chimney.

SUMMARY OF THE INVENTION An object of the present invention is,therefore, to provide a heat preserving boiler incorporating noveloutlet and inlet air passages which overcome the above-explaineddisadvantages of conventional boilers and prevent dangerous, uneconomicand incomplete combustion caused by inefficient air exhaustion which isattributed particularly to the counter-blow in the chimney.

Another object of the present invention is to provide a heat-preservingboiler, having the above-mentioned characteristics, wherein the exhaustair is utilized to increase efficiency by preserving the heat in,as wellas increasing the heat applied to the boiler content.

Yet another object of the present invention is to provide aheat-preserving boiler, having the above-mentioned characteristics,wherein the chimney can be made very compact, thus reducing theproduction cost.

A further object of the present invention is to provide aheat-preserving boiler, having the above-mentioned characteristics, andwherein the construction is such as not to limit placement of theboiler, so that the boiler may be installed in places where verticalchimneys cannot be used.

According to the present invention briefly summarized, there isprovided, in a heat-preserving boiler having a water tank therein, aflue pipe extending vertically within the water tank, a combustionchamber disposed under the water tank, and a water admission arrangementand a water delivery system connected with the water tank, an apparatuswhich comprises, in combination, a drum disposed over the water tank andforming an annular downward outlet air passage between the outside wallof the water tank and the in-- side wall of the drum, the upper endplate of the drum making a ceiling slightly above the flue pipe,a-partition cover positioned over the drum and forming an annular upwardoutlet air passage between the outside of the drum and the inside of thecover, the cover including a concentrical opening in the upper platethereof, a housing disposed over the cover and forming an annular inletair passage between the inside of the housing and the outside of thecover, the housing including a concentrical opening in the top platethereof, and the inlet air passage being connected with the combustionchamber through the lower end portion of the cover, an inlet ductconnected with the opening of the housing, and an outlet duct connectedwith the opening of the cover to lead exhaust gases to atmospherethrough the outlet air passages, the outlet duct being disposed withinthe inlet duct to form an extended inlet air passage between the outersurface of the outlet duct and the inner surface of the inlet duct.

BRIEF DESCRIPTION OF THE DRAWING The above-described and other objectsand features of the present invention will become more apparent from thefollowing specification, especially when read in conjunction with theaccompanying drawing, in which:

FIG. 1 shows an elevational section of a preferred embodiment of thepresent invention;

FIG. 2 is a partial rear side view of the apparatus shown in FIG. 1;

FIG. 3 is a cross-sectional view taken from line III III of FIG. 1looking in the direction of the arrows;

FIG. 4 is a cross-sectional view taken along line IV- IV of FIG. 1 andlooking in the direction of the arrows, and

FIG. 5 is a cross-sectional view taken on line VV of FIG. 1 looking inthe direction of the arrows.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing,and more particularly to FIG. 1 thereof, a preferred embodiment of thepresent invention comprises in its innermost part a cylindrical watertank 1 with a flue pipe 10 provided coaxially in the central portion ofthe water tank 1. The outer circumference of the water tank 1 is coveredwith a hollow cylindrical drum 4 having an inverted U-shape incross-section. Between the water tank 1 and the drum 4 is an appropriateannular space forming an annular downward outlet air passage 2. Theupper end circular plate of the drum 4 makes a ceiling 3 just above theflue pipe 10 of the water tank 1. A hollow cylindrical partition cover 6is lined with suitable heatproof and heat-preserving material such asglass wool, asbestos, or the like. The partition cover 6 is sopositioned as to cover the internal drum 4 and to provide an appropriateannular space between the lined inner circumferential surface thereofand the outer circumferential surface of the drum 4. The annular spaceforms an upward outlet air passage 5 which is in open communication withthe downward outlet air passage 2 at the lower end portion of the drum4.

Thus, vertically and coaxially through the water tank 1 at the centerthereof, the flue pipe 10 extends from the upper end portion of acombustion chamber 9 to the upper end portion of the water tank 1 tocommunicate with the outlet air passages 2 and 5.

The partition cover 6 is covered over the outer circumference thereofwith a hollow cylindrical housing 8. An annular space constituting aninlet air passage 7 is formed between the inner circumferential surfaceof the housing 8 and the outer circumferential surface of the partitioncover 6. The inlet air passage 7 is in open communication with thecombustion chamber 9 through a plurality of vent holes 1 l drilledthrough the lower end portion of the partition cover 6.

An outlet duct 12 communicates with a concentrical circular opening cutin the ceiling of the partition cover 6 an, thus, opens to the upwardoutlet air passage 5. An inlet duct 13 communicates with a concentricalopening in the ceiling of the housing 8 and, thus, opens to the inletair passage 7. The outlet duct 12 may be disposed coaxially oreccentrically within the inlet duct 13.

in this preferred embodiment as shown in FIG. 1, the outlet duct 12 andthe inlet duct 13 turn at a right angle at a point slightly above theceiling of the housing 8, so

that the two ducts extend rearwardly. The horizontally extended portionof the outlet duct 12 is positioned eocentrically upward within theinlet duct 13. The open end 14 of the outlet duct 12 protrudes slightlybeyond the open end 15 of the inlet duct 13.

The heat-preserving boiler in this embodiment is further provided with awater supply pipe 16 connected to the lower portion of the water tank 1and a hot-water outlet pipe 17 extending to the outside of the boilerfrom the upper portion of the water tank 1. A gas burner 18 is alsoprovided and a gas supply pipe therefor is connected to an automatic gasflow control apparatus 19 that controls the flow of gas by detectingprecisely the temperature of water inside the water tank 1. Asillustrated in FIG. 1, the heat-preserving boiler of this embodiment isproperly installed to a wall D through a fixing hole 20 providedthereinfor the inlet and outlet ducts 13 and 12 which are more firmly held bythe fixing metal parts 21.

The novel operation of the apparatus in accordance with the presentinvention is described in detail hereinafter. After filling the watertank 1 with fresh water through the water supply pipe 16, the gas burner18 is tired. This heats up the combustion chamber 9, and heated air andexhaust gases pass upwardly through the vertical flue pipe 10. Thus,water in the water tank 1 is heated at the bottom of the water tank 1 aswell as centrally through the wall of the flue pipe.

The heated air and gases ascending through the flue pipe are turned fromtheir upward movement by the ceiling 3 of the internal drum 4, and thendescend through the outlet air passage 2, heating the outercircumferential wall of the water tank 1 with their remaining heat. Thisincreases the heating effect on the water inside the water tank 1.

When the heated air and gases reach the lower end of the outlet airpassage 2, they turn upward, entering the outlet air passage 5. At theend of their upward movement in passage 5, the heated air and exhaustgases enter the outlet duct 12 to be completely discharged.

Supply of fresh air to the combustion chamber 9 is properly carried outby inflow of air from the opening of the inlet duct 13. The inflow ofair passes through the inlet duct 13 into the inlet air passage 7. Theair is further lead into the combustion chamber 9 through the pluralvent holes 1 1.

As has been explained, the outlet duct 12 extends coaxially oreccentrically within the inlet duct 13, and

the opening 14 of the outlet duct 12 protrudes slightly beyond theopening 15 of the inlet duct 13. Consequently, the openings 14 and 15 ofthe outlet and inlet ducts 12 and 13 respectively, being offset ondifferent planes, the inflow of the fresh air and outflow of the heatedair do not affect each other and eliminate undesired effects of the windpressure against the two openings 14 and 15. Furthermore, the describedconstruction is such that unnecessary and harmful outside air is notallowed to enter the outlet duct 12. Thus, any possibility ofcounter-blow of exhaust air into the combustion chamber 9 caused bycounter-blow of fresh air into the outlet duct 12 is prevented. On theother hand, a constant supply of fresh air into the combustion chamber 9is obtained by the inflow of air through the inlet duct 13 and the inletair passage 7 which is completely separated from the outlet air passage5 by the partition cover 6. This provides stable and effectivecombustion in the combustion chamber 9. Furthermore, the remaining heatof the heated air is effectively utilized to heat the circumferentialwall of the water tank 1 as it is being exhausted through the outlet airpassage 2.

When the water inside the water tank 1 reaches a predeterminedtemperature, the gas burner 18 is shut off. At .this moment, thetemperature inside the flue pipe 10 is almost equal to that in theoutlet air passages 2 and 5. Thus, natural air convection ceases sothat, consequently, the heated air is effectively utilized to preservethe temperature of the hot water inside the water tank 1.

The heat-preserving boiler as described does not require any specialchimney or the like for the outflow of the exhaust air. It can be simplyand easily set up in a desired and appropriate location with the ductends 14 and 15 projecting slightly beyond the wall of the location andthrough an opening provided in such wall. This eliminates to a greatextent restrictions as to placement and installation of conventionalboilers.

Although a certain specific embodiment of the invention has been shownand described, it is obvious that many modifications thereof arepossible. The invention, therefore, is not intended to be restricted tothe exact showing of the drawing and description thereof, but isconsidered to include reasonable and obvious equivalents.

We claim:

1. The combination with a heat-preserving boiler, including a water tanktherein, a flue pipe extending vertically through said water tank, acombustion chamber disposed under said water tank, water admissionmeans, and water delivery means connected with said water tank, of atubular drum having a wall at its upper end spaced from and surroundingsaid water tank to form an annular downward outlet air passage betweenthe outer surface of said water tank and the inner surface of said drum,the upper end wall of said drum defining a ceiling above said-flue pipe,a tubular cover having a wall at its upper end with an opening thereinand positioned over said drum to form an annular upward outlet airpassage between the outer surface of said drum and the inner surface ofsaid cover, a tubular housing having a wall at its upper end with anopening therein and disposed over said cover to form an annular inletair passage between the inner surface of the hous- IO60l2 0156 ing andthe outer surface of said cover, said inlet air passage being connectedwith said combustion chamber through openings at the lower end portionof said cover, an inlet duct communicating with said inlet air passageand connected to said opening in the upper wall of said housing, and anoutlet duct connected with said opening in the upper wall of said coverand communicating with said outlet air passages to lead exhaust air toatmosphere, said outlet duct being disposed within said inlet duct toform an extended inlet air passage between the outer surface of saidoutlet duct and the inner surface of said inlet duct.

2. The combination as set forth in claim 1, in which said outlet duct isdisposed coaxially within said inlet duct.

3. The combination as set forth in claim 1, in which said outlet duct isdisposed eccentrically within said inlet duct.

4. The combination as set forth in claim 1, in which said outlet ductprojects out from the open end portion of said inlet duct.

5. The combination as set forth in claim 1, in which said inlet andoutlet ducts turn substantially at a right angle above said housing,said inlet and outlet ducts maintaining their parallel relationship toeach other throughout their lengths.

6. The combination as set forth in claim 1, in which said cover is linedwith glass wool material.

7. The combination as set forth in claim 1, in which said cover is linedwith asbestos material.

1. The combination with a heat-preserving boiler, including a water tanktherein, a flue pipe extending vertically through said water tank, acombustion chamber disposed under said water tank, water admissionmeans, and water delivery means connected with said water tank, of atubular drum having a wall at its upper end spaced from and surroundingsaid water tank to form an annular downward outlet air passage betweenthe outer surface of said water tank and the inner surface of said drum,the upper end wall of said drum defining a ceiling above said flue pipe,a tubular cover having a wall at its upper end with an opening thereinand positioned over said drum to form an annular upward outlet airpassage between the outer surface of said drum and the inner surface ofsaid cover, a tubular housing having a wall at its upper end with anopening therein and disposed over said cover to form an annular inletair passage between the inner surface of the housing and the outersurface of said cover, said inlet air passage being connected with saidcombustion chamber through openings at the lower end portion of saidcover, an inlet duct communicating with said inlet air passage andconnected to said opening in the upper wall of said housing, and anoutlet duct connected with said opening in the upper wall of said coverand communicating with said outlet air passages to lead exhaust air toatmosphere, said outlet duct being disposed within said inlet duct toform an extended inlet air passage between the outer surface of saidoutlet duct and the inner surface of said inlet duct.
 2. The combinationas set forth in claim 1, in which said outlet duct is disposed coaxiallywithin said inlet duct.
 3. The combination as set forth in claim 1, inwhich said outlet duct is disposed eccentrically within said inlet duct.4. The combination as set forth in claim 1, in which said outlet ductprojects out from the open end portion of said inlet duct.
 5. Thecombination as set forth in claim 1, in which said inlet and outletducts turn substantially at a right angle above said housing, said inletand outlet ducts maintaining their parallel relationship to each otherthroughout their lengths.
 6. The combination as set forth in claim 1, inwhich said cover is lined with glass wool material.
 7. The combinationas set forth in claim 1, in which said cover is lined with asbestosmaterial.